Mold and method of casting



Nov. 27, 1934. E. G. FAHLMAN MOLDVAND METHOD OF ASTING Filed May 2, 1952 INVENTOR ATTORNEYS Everett G'. Falz/Iman BY Patented Nov. 27, 1i34 A UNITED STATES PATENT `orrlci:

, 1,982,423 M oLD AND METHOD oF cAs'rmG Everett G. Fahlman, Cleveland, Ohio, assignor to The Permold Company, Cleveland, Ohio, a corporation of Ohio Application May 2, 1932, Serial No. 608,715

4 Claims. (Cl. 22-212) This invention relates to the casting of alumigate 10. Mounted on the base plate l is the num and alloys thereof, and more particularly to frangible core 8 which, with the mold cavity rethe casting of such metals in semi-permanent cesses and 6 above mentioned, define a thinmolds. walled. semi-cylindrical cavity with ends, such 5 Many castings of aluminum or alloys thereof as might be used to cast the cleaning nozzle of a are formed in permanent molds, due to the advacuum cleaner. It is, however, desired to cast vantages of this method of casting. In the case 0n this thin-Walled, h0110W Structure e heavy 111g of certain castings having hollow interiors of andthe mold section 3 is accordingly provided more or less complex nature, however, frangible With the recess 4 t0 formthis 111g- 10 cores, such as of sand, are employed, the combi-v There is provided, OIJDOsite the cavity OI the 65 nation of sand core and metal mold parts being lug 4, a recess in the send core 9. This recess is known as semi-permanent mold casting, thin and flat, being preferably about als inch in In the case of hollow castings of relatively thin thickness for the casting shown in the drawingsection, Where it has been desired to form solid Its aree depends 0n the Volume 0f metal t0 be lugs 0r sin-mar heavy portions 0n the outer side Cast intO the 111g 4. The recess iS therefOle llSllal- 70 of the casting directly adjacent to the thin sec- 1y comparatively narrow when it is desired to protion, great diiilculties have beenencountereddue vide a casting having a lug Such as describedto the formation of sinks and cracks adjacent In cese 0f Other heavy structures it may assume to the junction of the .lug and thin casting sec- Other forms. es Will be later noted.

tion. With the ordinary construction of a sand core 75 An object of this invention is to overcome the it is found that al seriously large number of castaforementioned diillculties and to provide a ings ShOW imperfection in the ferm 0f creeks, method of forming castings of aluminum or alsinks. etc. adjacent the bese 0f the heavy 111g. loys thereof of widely varying sections in semi- When, however, the sand core is provided with a permanent, molds, r recess as described, it is found that diiiiculties of 80 Another object is to provide a method of castthis sort are largely or wholly overcome, and that ing solid lugs on thin sections cf houow aluminum inthis wav it is possible to cast heavy lugs on castings, castings of generally thin section, and to produce A further object is to provide an improved generally perfect castings without the defects method of casting aluminum or alloys kthereof above mentioned. I do not here advance with 85 in semi-permanent molds to form castings of in- .certainty any eXple-netcn 0f this Phenomenon. trca interior and of widely varying section. However, rbelieve it t0 be possibly due t0 the Another object is to provide, for the semi-per. fact that the metal in the recess in the sand core manent mold type of casting aluminum and alc0018 more' rapidly than dees the metal in the loys thereof, an advantageous method of chilling thin section adjacent and much more rapidly 90 uniformly the casting metal forming heavy and than the metal in the heavy lug. and accordingly thin sections of the article being cast, solidifles before the metal in either of the other other objects will be apparent to those skilled two locations. The metal in the recess in the in the art from the disclosures herein made from send core being very thin, the relation of its area 40 the accompanying drawing, wherein to volume is large and consequently it solidies 95 Figure 1 is a. vertical section through e. permcrapidly in spite of the low heat conductivity of nent mold and casting therein constructed acthe frangible core. When solidified, the concordjng to the method outlined herein and duction of heat through the thin chill is large through the Irangible core cooperatively assoand the chill conducts heat into a relatively large ciated therewith; and l area of the frangible core and will therefore act100 Fig. 2 is a horizontal section taken along the as a solid metal chill to the rest of the casting at line 2--2 of Fig. 1. that point. In this way the metal of the lug is The mold as shown somewhat diagrammaticooled as rapidly as is the metal of the thin sec- 1 cally is designed to cast a hollow object such tion immediately adjacent, and the aforesaid as might be used as the cleaning nozzle of a sinks and cracks in and around this structure 105 vacuum cleaner and consists of a base plate 1 are prevented. After the casting has solidified supporting the mold sections 2 and 3. These mold and the franglble core removed it is a very easy sections are recessed to form mating halves of a matter, owing to the thin cross. section of the mold cavity 5 and 6 and also cooperatively rechill, toremove iti! desired.

cessed to form the pouring sprue cavity '1 and Itwillthusbeseenthatlhave devisedamethod .110

of chilling heavy sections of castings adjacent thin `sections, which method is very much more easy to use than methods heretofore used for this purpose, and in which the chill is in a sense made integral with the casting and thereby has superior heat-conducting qualities therefrom. It Will also be seen that it can be removed from the casting easily and that no defect in the surface or internal structure results thereby.

Due to its thin cross section and large area, the chill disclosed herein utilizes only a small amount of casting metal and its configuration is such that for purposes of description it may be termed a leaf chill.

While I have described and illustrated this invention as a method of forming heavy lugs on hollow castings of generally thin cross section, it is to be noted that the method is much more generally applicable. For example, the castings may be iiat though of thin cross section. Furthermore, the lugs or other thick cross section, the casting of which is to be facilitated, instead of being long and having a relatively small base attached to the casting as shown herein, may be heavier and more than one leaf chill may be used. Instead of being in the form of a lug it may be of rib form, in which case either a number of leaf chills may be placed opposite it, or one or more long leaf chills may be provided running along its axis on the other side of the thin section of the casting of adequate chilling eiect for the rib orV other heavy section to be cast.

While the drawing describes a casting of a' generally hollow nature with a frangible core, this method is not limited thereto but is applicable to any semi-permanent mold where there are one or more thick sections adjacent to the thin sections.

It will thus be seen that I have overcome in a very simple manner a diiiiculty in the use of semipermanent molds, which diiculty resides in the general problem of casting heavy sections adjacent thin sections, particularly when suchthin section is dened by a frangible core of low heat conductivity and of low specific heat. I have, by a very simple method, succeeded in increasing the apparent conductivity of such frangible mold members and utilizing a greater volume thereof for cooling purposes than ordinarily comes into function. I have, moreover, provided what is in effect a chill which, through its integral character with the rest of the casting, has a great capacity for conducting heat away'therefrom and which, through its thin cross section and large area, can be leasily removed, if desired, .from the finished casting without marring the surface thereof, without using a great deal of metal, `and without disturbing the internal structure of the casting.

Furthermore, it is to be understood that the particular forms of apparatus shown and described, and the particular procedure set forth, are presented for purposes of explanation and illustration and that various modifications of said apparatus and procedure can be made without departing from my invention as deiined in the appended claims..

What I claim is:

1. A semi-permanent mold comprising metal mold members recessed to define the exterior wall of a molding cavity and a frangible core member within said cavity and defining the interior wall of the molding cavity, said mold members being formed to provide a cavity which is generally thin in cross section and which has a portion of relatively thick cross section, said frangible core member having a recess of thin cross section and relatively large surface area opening to the portion of the cavity of thick cross section.

2. A semi-permanent mold for producing castings composed of a relatively thin section and a relatively thick section comprising a metal mold member and a frangible mold member arranged in spaced relationship to each other to form a mold cavity having a comparatively thin cross section, said metal member being recessed to form a portion of the mold cavity for casting the thick section, and the frangible member having a relatively thn recess therein opposit: to the recess of the metal member in which the thick section is formed, to provide a space in which a relatively thin layer of metal may be cast in opposed relation to the thick section.4

3. The process of forming castings having a relatively thick section and a relatively thin sec-` tion, which comprises arranging a metal mold member having a recess therein and a frangible mold member in opposed relationship to each other to define a mold cavity, casting metal in said cavity to form the relatively thick and thin sections and simultaneously causing a portion of the casting metal to flow in a recess in the frangible mold member opposite the thick section having such a cross section that the metal in the recess of the frangible mold will solidify before the metal in the thick section, and conducting heat from the thick section during'theobling thereof Y Y by means of the solidified metal formed in the frangible mold.

4. In the process of forming castings having a relatively thick section and a relatively thin section in a semi-permanent mold in which a metal mold member forms the outer surface of the casting cavity and hasl a recess therein to form the thick portion, and a frangible mold member forms the inner surface of the casting cavity, the steps which comprise pouring metal in the casting cavity to form the relatively thin and thick sections and simultaneously causing a portion of the molten metal to flow into a narrow recess in the frangible member having such a cross section that metal in the recess will solidify before the metal in'thethick section, and conducting heat from the metal in the thick section during the solidiflcation thereofiby means of the solidified metal formed in the frangible mold. d

EVERET'I G. FAHLMAN. 

